L22 conservation biology

L22 conservation biology - BILD 3 July 26, 2010 One species...

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BILD 3 July 26, 2010 Woodruff: conservation biology 1 One species has irrupted on the planet A species that seeks to control nature Uses 40% of global NPP State of the World Forests, wetlands, mangroves all half gone grasslands 70% degraded Lakes acidi±ed, water contaminated Oceans polluted, overharvested, turning sour Coral reefs 40% degraded Atmosphere warming 2–3 o C Ecosystem services threatened Biodiversity: onset of the sixth great mass extinction 20-50% of area occupied by a particular biome today will no longer be suitable When CO 2 x 2 Conservation: Management of human use of the biosphere so that it may yield greatest sustainable benefit to present generations while maintaining its potential to meet needs & aspirations of future generations Conservation is positive Preservation & maintenance Sustainable utilization Restoration & enhancement Conservation biology as a field of scholarship has its roots here in Solis Hall in October 1978 CAUSES OF EXTINCTION/THREAT 1. 2. Over-exploitation 3. Species introductions Predators/pathogens; Competitors 4. Secondary effects Commensals; Pollinators/dispersers; Pesticides 5. Natural catastrophes 6. Climate change 7. Genetic erosion Why is habitat area so important? S = CA z NO. OF SPECIES DOUBLES WITH 10X INCREASE IN AREA NOW FUTURE Log HABITAT AREA LOG SP. NO. A 10-fold decrease in area cuts species number in half. Half the larger vertebrates threatened with extinction.
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BILD 3 July 26, 2010 Woodruff: conservation biology 2 WHY DO WE SAY THERE IS A BIODIVERSITY CRISIS? Most significant cause of species extinctions: habitat destruction Most species live in tropics 50% of tropical forest degraded or gone by 2020 24% mammal species, 24% reptiles, 32% crabs now threatened with extinction CULTIVATED LANDS WHY DO WE SAY THERE IS A BIODIVERSITY CRISIS? 10 million species of which 2/3 live in tropics 40% of tropical forest degraded by 2020 So >700,000 sp. will go extinct in tropical forests and >1 million species worldwide Over 20 years = 15,000 sp./year (guesstimate) Current mammalian rate: 1 every 4 years K-T (dinosaurs) extinction rate of 1 every 10,000 years. Today’s overall extinction rate 1,000x background 40 hectares of habitat lost every minute [Half a football field every second] Causes of endangerment 1. Habitat destruction Spotted owl San Diego County has more threatened, legally protected species than any other. Cause of endangerment: habitat loss. Stephens kangaroo rat
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This note was uploaded on 07/28/2010 for the course BIOLOGY BILD 3 taught by Professor Davidwoodruff during the Summer '10 term at San Diego.

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L22 conservation biology - BILD 3 July 26, 2010 One species...

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